dictator

English dictator comes from Latin dictātor, a chief magistrate, which traces to dictō ("dictate, prescribe") and ultimately dīcō ("say, speak"). By surface analysis it's simply dictate + -or, literally "one who dictates."

Old English already borrowed a form of the word, tictator, to describe the absolute ruler of the Roman Republic, showing the title's meaning of supreme authority carried over early into English use.

It shares its root with dictate, both descending from Latin dīcō, "to say or speak."